Avoid the pitfalls when designing for galvanizing with this handy wall chart for your office. APG has had over 55 years experience, so when it comes to Galvanizing- our motto is DO IT ONCE, DO IT RIGHT!
Don’t?get caught out with stupid unavoidable mistakes, grab your handy wall chart below and of course our experiences sales guys are always happy to assist with any queries you may have. 07 4040 7000
It is important to consider the corrosion protection of ferrous articles when they are being designed. The key factors to consider when designing for hot dip galvanizing are the design’s impact on:
– Safety during the process
– Quality of the coating
– Aesthetics
This guide provides general information on basic design and detailing practice, including venting and draining, to assist in the safe and quality hot dip galvanizing of articles.
APG_Design Guide for Hot Dip Galvanizing – Best Practice Venting and Draining
The Sydney Harbour Bridge’s use of ferrous alloy presents a significant challenge in terms of protecting the structure from the ravages of corrosion. It is indeed a cruel irony that our most-used alloy for structures, steel, is also the one most damaged by exposure to the atmosphere. Steel, unlike many other metals, does not exhibit passivity. Passivity occurs when a metal or alloy reacts with the oxygen in the atmosphere to create a non-porous oxide film that protects the material from further oxidation. Unfortunately, steel oxidises to form rust, a corrosion product that is porous, which means that the rust exposes more metal to oxidation. On large panels, this rust may simply be surface corrosion which is really more an aesthetic problem in the short term and a minor problem in the long term.
Where this lack of passivity becomes a huge problem is in places where water can pool or seep into. A riveted structure like the Sydney Harbour Bridge is fertile ground for crevice corrosion to occur through concentration cells.
Crevice corrosion occurs when a small cavity or gap is created which allows water to pool. This then brings about a concentration cell. A concentration cell is where there is an electrolyte (a fluid capable of carrying current) with differing levels of aeration or concentration of oxygen. Areas of high oxygen concentration become the cathode while areas of low concentration become the anode.
The diagram below illustrates why this is a problem for a riveted structure. The rivet when exposed is not sealed against the entry of water; this means that water may seep into the small space between the rivet and the rivet hole in the plate. Any water in this area is likely to suffer differentials in aeration levels and we now have a situation suited to corrosion. If water is drawn into areas A and B, A would have more oxygen and become the cathode, while B would become the anode. This means part B, hidden from inspection, would slowly degrade and weaken the joint. Moreover, the gap between the plates, part C, could also become filled with water and create a concentration cell between the plates.
As the corrosion process continues, the corrosion product (iron oxide) takes up a greater volume than the original metal. Thus, as the corrosion cell grows, significant forces develop to tend to force the joint apart.
A rivet holding two steel plates together.
While the gaps are exaggerated for this illustration, water can certainly seep into such places and create concentration cells.
How can this be avoided? In modern structures, we could circumvent this by galvanising the steel. By coating the steel with zinc we protect the structure from rusting because zinc will corrode in preference to steel. This is why galvanised steel is so common in steel structures nowadays.
As the Harbour Bridge is not galvanised, our only other solution is to take the approach used for cars: paint it. The paint effectively seals the steel from the atmosphere and alleviates rust formation. The problem with paint is that, unlike galvanising, it does not protect the steel if the steel becomes exposed. Additionally, the paint is degraded by ultra-violet radiation and weathering, so it must be continually replaced. Unlike a car, which is garaged and often well cared for, the Sydney Harbour Bridge?s paint takes a beating and must be continually replaced.
The original paint primer was lead oxide based with the finishing coats based on micaceous iron oxide. Both these paints are deleterious to the environment and the RTA is removing original paint layers and using modern coating materials in their place.
The initial three coats of paint placed on the bridge used 272 000 litres of paint. The replacement of the paint is a regular part of maintenance and an ongoing cost.
article?from :https://sydney-harbour-bridge.nesa.nsw.edu.au/engineering-studies/corrosion.php
Above: Stephen Pollard, Ron Pollard and Brian Coates of APG Galvanizing
The annual Australian Galvanizers Association (GAA) conference was once again held to present new innovations in Hot- dip galvanizing to the industry and of course relax with colleagues and associates for a few days as we draw closer to the end of another year. As well as a few coldies we are also there to announce the winner from the submissions for the 2018 Excellence in Hot-Dip Galvanizing Sorel Award.
Presented annually, the Excellence in Hot-Dip Galvanizing Awards honour the finest achievements in the use of hot-dip galvanizing in an ideal, creative, innovative or monumental fashion.
Hot-dip galvanized steel is used in myriad applications throughout various industries. The Sorel Award is presented to a stand out application and design featuring Hot-dip galvanizing at the core of the project. This year’s award was one by Kingfield for Borals Concrete batching plant. Congratulations!
Pollards Galvanizing was founded by Ron Pollard in 1966 in the industrial suburb of Bungalow, Cairns. From day one, the mission was to “treat everyone like family” whilst providing a service of the highest quality. Some 20 years later moved to Kenny Street, Portsmith where the APG offices still sit today. They expanded the Galvanizing component to Townsville in 2010, And changed the name to Australian Professional Galvanizing (APG) streamlining the process of operations and expanding their reach from Rockhampton to Cairns and inland to Mt Isa.
Stephen Pollard CEO of APG today, “Our decision to expand our premises and move the Galvanizing component to Townsville was our commitment to bring our quality, customer-first mindset to more FNQ buying customers. Our quality management systems and lean manufacturing disciplines within our culture, help bring the best possible prices to our customers so we can continue in the business of galvanizing for another 50 years!”
We have continued to grow and our workmanship meets the minimum of AS/NZS 4680/2006 quality standard. We are also members of the Galvanizers Association of Australian giving our customers further assurances.
For any further information regarding Hot-dip Galvanizing contact, the team-APG are willing to enter into a quoting arrangement for larger scale projects and actively encourage our customers to negotiate with us.
Do it once. Do it Right – Galvanize.
THA’S WHY THOSE IN THE KNOW – HOT DIP!
Since 1967 APG has listened to you the fisherman, to come up with the most efficient trawl door on the Australian market today. The Bison trawl door will save you around 15% on fuel costs, it can be trawled at optimum speed a lower engine RPM with maximum net spread with less drag enabling you the fisherman to cover more ground each night thus increasing you catch. The Bison door spreads your nets to maximum efficiency, which means you miss less product per shot. Due to superior design in the hydrodynamics, the Bison door has approximately 75% of the surface area of an equivalent wooden otter or V door and maintains its spread with the product in the cod-end. The Bison door is fabricated from steel and then HOT Dip Galvanized, this extended the lofe of the door and practically eliminates maintenance. The refurbishment of the Bison trawl door is a simple and inexpensive operation, they can be galvanized as often as you require, wear plates are easily replaced from APG and can be fitted using a hammer and shifting spanner.
Setting up the boards for your particular needs is an easy exercise, all towing parts are adjustable and doors can be fine-tuned to suit your trawl nets and vessel, additional weights are available on request, which shows you how to adjust an setup the boards to give maximum performance. APG Pty. Ltd. has the facilities to individually meet your requirements, whether to fulfil orders for new doors or refurbishments. The Bison trawl door was designed after extensive testing at the Australian Marine College using a scaled-down model of the doors and working with fisherman on their trawlers. The Bison trawl door comes in various sizes from Try doors up to 11’s and 12’s with such a large range to choose from we can cover all vessel /net combinations. At present, over 70 fishing companies are using Bison trawl doors, these include Raptis & Sons, New Fishing, Australian Tiger fisheries and many from overseas. Eg; Argenova SA from Argentina, Penwarden Holdings & Sanford Pty. Ltd for New Zealand.
